Mechanical time fuze



United States Patent [72] Inventors Dragolyoub Popovitch Denville, NJ.; Roy B. Nystrom, East Northport; Melvin Eneman, New York, NY. App]. No. 682,441 Filed Nov. 13,1967 Patented Dec. 15, 1970 Assignee the United States of America as represented by the Secretary of the Army. by mesne assignments MECHANICAL TIME FUZE 15 Claims, 11 Drawing Figs.

0.5. CI 102/71, 102/84 Int. Cl F42c 9/02, F42c 9/04, F42c 9/00 Field of Search 102/71, 83, 84, 74, 75

References Cited UNITED STATES PATENTS 8/1944 Weisz l02/84X Primary Examiner-Benjamin A. Borchelt Assistant Examiner-Thomas H. Webb Attorneys-Harry M. Saragovitz, Edward J. Kelly, Herbert Berl and Lawrence S. Epstein ABSTRACT: The invention is designed to be an all-purpose fuze and consists of four mechanical modules and an explosive train, all housed in a two-piece body.. The modules comprise a digital setting module including a setting gear housing in order to set the time for exploding, a timing mechanism module which contains a timing movement and a scroll operative with the digital module, an arming and firing trigger module, and a boresafe arming delay movement. The fuze is set in a safe position for delivery and stockpile. For function it can be set to detonate on impact or after a timing delay which in one instance is from 0.3 to 200 seconds after firing.

PATENTEUDEEISIQIB I sum 5 (1F 3 INVENTORS DRAGOLYOUB POPOWTCH ROY 5. NYS'TR MELVl/V EMA -(9 v I of. 4.

ATTORNEYS PATENTEDBEEI 5I97G 3,547,034

sum 5 or a INVG'NTORS:

PRAGOL Youa POPO w 7'6H ROY a. N vs mom n. v/ v ENE m/w 8. 5f ATTORNEYS PATENTEDDECI 519m 3; 547', 034

sum 7 0F 8 INVENTOR DRAGOLY B P'OPOVITCH R01 5. NKSTRO MELVIN E/YEM Y M714.

MECHANICAL TIME ruzn Progress in artillery long ago had made inadequate the conventionally utilized fuze known as thelfilunghans fuze. This fuze is a high frequency adaptation of the cylinder. type ferent spin rates of the round. This. spin varies from one weapon to another and from one charge to another for the same weapon. Further, its best performance is about 0.5 to l.0 percent accuracy under the most severe new weapon conditions. It thus is necessary to stock a variety of different versions of the basic mechanism to optimize the performance in different shells. Some recent modifications made the Junghans scapement substantially spin insensitive and'rugged enough.

to withstand extreme ranges of firing environments. However, this did not change the basic nature of theescapement, nor did it improve the basic accuracy characteristics of the Junghans escapement.

A more accurate detached lever escapement was conceived about l750.Later refinements made'it extremely accurate in time and now has completely replaced'the older cylinder type movement in ordinary watches and clocks. The principles of this detached lever escapement have-been utilized in the instant invention. Thus, both spin insensitivity and accuracy in time are now accomplished.

The fuze of the invention is a mechanical time fuze comprising a setting module, a timing mechanismvmodule, an arming and firing trigger module, a boresafelarming-delay module, and an explosive output element all housedin a two piece body. Additional features include a direct-acting pointdetonating element and a dual-purpose explosive output element suitable to initiate either high explosive by detonation or pyrotechnic materials without detonation.

Thus, several significant advances inthe state of the art are provided by the invention:

1. Safety Setback and spin, in that order, are required to initiate fuze timing and arming after the fuze is firstset from its safe-locked condition. Further, when set for time, fuze arming is withheld until a preset built-in interval prior to the set time;

2. Versatility The fuze can function accurately and reliably when fired with shell from guns and mortars'having less than 1,000 g.s setback to more than 30,000 g.s setback and spin rates from less than 2,000 r.p.m. ,to more than 30,000 r.p.m. It can be set to functionfrom zero time after firing to 200 seconds. Greater duration, to multiples of 200 seconds would require relatively small design changes if longer durations are needed. It can reliably initiate high explosive, propellant or black powder. It conforms to the shape of the shortest intrusion standardized American-British-Canadian-Australian (ABCA) fuze contour and mounting configuration for 75mm. and

larger shell. These characteristics permit this single fuze to be used with all known ABCA shells which use time fuzes; Accuracy The fuze can be set to a fraction of 0.1 second throughout its timing range. The mean-time of fuze functioning has characteristically been within 0.1 second of set time at 5 second settings and within 0.25 second of set time at 115 seconds. This should greatlyfacilitate its use without extensive range tables. The standard deviation of fuze functioning time is relatively invariant from non spinning laboratory conditions to 15,000 r.p.m.- and 30,000 r.p.m. in the shell, This standard deviation has been from about 0.03 second at 5 seconds setting to about 0.2 second at 115 seconds. This greatly improved fuze accuracy permits the most economic exploitation of currently available ballistic accuracy;

Handling The fuze is a completely sealed package which can be set through an arrangement similar to that of a 75 the primer ring.

waterproof watch. Setting requires very low torque such as may be obtained by use of a small screwdriver, or even a small coin. The setting of Safe, PD, or time is directly visible; and in particular, the time settings are direct reading digits in seconds with direct reading line markings to tenths of seconds. These improvements reduce the care needed in handling; the special wrenches or other tools needed for setting; the training needed to handle time fuzes; and the time, care and number of personnel needed I to set fuzes at the gun battery.

, The primary object of the invention is to provide a fuze whichis versatile in use and which may be retained in storage or at the gun in a safe-set condition, or preset for point'detonation or preset for a specific functioning time delay.

1, Another object is to provide a fuze which is extremely accurate in its timing range to obtain substantially an overall negligible error. As a result, the need for extensive range tables is no longer required.

Still another object is to provide a fuze contained as a completely sealed package capable of being set through an arrangement similar to that of a waterproof watch.

An advantage of the invention is to permit settings requiring very low torque.

Another feature of the invention is to provide time settings which are visible as direct reading digits.- I

And yet another object is to reduce the time required to train personnel to handle fuzes as well as the number of personnel required to set fuzes at the gun battery.

It is still yet another object to provide a multipurpose lead capable of being initiated by a relatively small detonator and one which may be used interchangeably with different types of explosives and propellants. i

These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present in- FIG. 5 is a section of the arming and firing triggermodule showing the setback spin arrangement,

FIG. 6 is an exploded view of the arming and firing trigger module and the bore safe arming delay module,

FIG. 7 is a plan view of the bore safe arming delay module with the top plate removed, 7

FIG. 8 is a bottom view of the scroll disc member and the various positions for the scroll pin follower,

FIG. 9 is a bottom view of the: digital counter with the seconds wheel element removed,

FIG. 10 is a plan view of another form of setting arrangement showing a slip clutch construction, and

FIG. 11 is a section taken on the line! l-ll of FIG. 10.

Referring to the FIGS. and particularly to FIG. 2, the mechanism of the fuze 20 is housed in an upper body (fuze ogive) 22 having a window area 24 at the nose portion The mechanism of the fuze 20 is composed of a digital setting module 26, a timing mechanism module 28, an arming and firing trigger module 30, and a boresafe arming delay module 32 the modules given from the nose-end of the fuze to the base, respectively. The mechanism is retained in the upper body by a threaded lower body member 34, which has additional threaded portions for fuze-to-shell and booster-to-fuze mounting (the latter is conventional and need not be further described). An external setting key .36 is seated in the nose of the fuze ogive 22 under the seal 38 and acts as the firing pin to The digital setting module, located at the nose-portion of the fuze 20, simultaneously sets and indicates the safe, pointdetonating (PD), or timing functions of the fuze. The setting module is designed to accommodate, either the inclusion or the omission of the PD element without modification. The external setting key functions also as the striker or firing pin for the PD function. Dual redundant lengths of mild detonating fuze (MDF) lead from the PD primer to the input face of the bore safe module. This arrangement was conceived to be, and has been demonstrated to be, significantly faster functioning than the more conventional flash-through PD explosive trains used with'current U.S. time fuzes. This greater speed affords V improved performance when used with I-IE shell intended to provide antipersonnel or antilight structure fragmentation and blast. The greater speed should also improve burst point visibility when the PD feature is used for registration of fire. The digital setting module consists of a digital counter mechanism 40 and a setting gear housing 42. (See FIGS. 2 and 3) The digital counter mechanism 40 consists of hollow setting shaft 44, the three digital counter wheels 46, the hundreds wheel 48, the tens wheel 50 and the seconds wheel 52 and the two counter wheel index pinions 54, (see FIG. 9), and a PD/Safe indicator flag 56. The index pinions 54 are located, one between the seconds and tens counter wheel and the other between the tens and hundreds counter wheel. They are generally placed in tandem. This arrangement is conventional in digital counters and need not further be described. The annular apex of the indicator flag 56 is slotted at 55 to receive the pin member 57 and is also provided with an axial aperture to receive therethrough the setting shaft 44. The shape of the indicator flag conforms to the divergent shape of the housing 60 of the digital counter mechanism 40 The reduced upper neck portion of the shaft 44 is slotted to receive thereon the setting key 36 to transmit torque from the setting key 36 to the setting shaft 44. The digital counter mechanism housing 60 is seated in position by a suitable slot engaging a pin (not shown) extending laterally from the setting gear housing member 42. The hollow setting shaft 44 is coupled directly to the setting pinion 62 which will turn the gear member 64 in the setting gear housing 42. On turning the gear member 64, the pinion member 65 in the setting gear housing 42 rotates and drives the ring gear 67 to thus turn the clock assembly 28. The members 64 and 65 are shown mounted on the same shaft member. This gearing arrangement provides a :1 reduction ratio from setting key 36 to clock assembly 28. Both the counter wheels 46 and the indicator flag 56 are observable through the fuze window 24 (see FIG. 2). The setting gear housing is in two sections, with the gear members 64 and 65 rotatably retained in the housing 66. (See FIG. 3) The gear retaining housing 66 is adapted to seat in the timing movement housing section 68. An annular axially bored ring 70 includes an extension flange 72 and is configured at 74 to receive the gear retaining housing 66. The annular ring 70 retains the fastening ring 76 thereon in a freely movable manner. The fastening ring 7'6 is threaded to the mechanism outer housing 78 to retain the timing mechanism module 28, the digital setting module 26 and the setting shaft 44 in cooperative position. Setting the fuze is accomplished by applying torque to the setting shaft 44 at the nose of the fuze through the setting key 36. The torque is transmitted from the setting shaft through the gear and pinion set, in the setting gear housing 42 to the ring gear 67 attached to the top of the timing mechanism. The pinion member 65 engages the ring gear 67 of the timing mechanism module 28. A vertical shaft 90, extends from the timing mechanism into the hollow setting shaft 44 of the digital module. The applied torque rotates the timing mechanism module 28, and thereby the timing scroll disc 86 for the set time desired.

The timing mechanism module 23 provides for the delay of fuze firing for a desired period of time (i.e., set time) and relates fuze settings made into the digital setting module to the amiing and firing trigger module 30. A torque washer 79, between the two modules prevents slipping of the elements. The timing mechanism module 28 is located beneath the digital setting module 26 and consists essentially of a timing movement member 80 having a detached lever escapement and a gear train 82, a prcwound clock mainspring 84 and a timing scroll disc 86. The mainspring arbor 84 is geared to the timing movement and is also fixedto the timing scroll 86. This arrangement causes the timing scroll. disc to rotate at the running rate of the timing movementsyvhen the timing movement is permitted to run. The timing seroll disc 86 has a spiral cam surface 88 in its lower face which accommodates a scroll follower pin 104, which is part of the arming and firing trigger module. The timing mechanism module represents a major advance in the art of mechanical time fuzes in that the much greater inherent accuracy of the detached lever escapement can now replace the five to ten times relatively poorer accuracy of the cylinder escapement which is now almost universally used in one or another of its many forms. In addition this inherently more accurate type of escapement has been applied in a form which is suitable for use under broader ranges of gun conditions and environments than any time fuze known to the inventors. A more detailed discussion of the timing mechanism module is provided in the copending application Ser. No. 774,231, filed Nov. 6, 1968.

The arming and tiring trigger module 30 performs two functions: arming delay rotor release and firing pin release. (See FIGS. 2, 3 and 4) Both functions are performed at the desired times by the actuation of'a rotor detent release lever 96 and or firing pin release lever 94. These actuations are controlled by the D-slots 98 and 99 (see FIG. 4) provided in a firing arm shaft 100. A firing arm 102 on the upper end of the firing arm shaft has a scroll follower pin 104 which is controlled by the rate at which the timing scroll disc 86 rotates (i.e., rate of the timing movement) p provided the scroll follower pin 104 is engaged along the spiral cam surface. A torsion spring 106 is retained on the shaft 100 to keep it against the control surfaces of the scroll member 86. A combination setback-spin detent arrangement 108 prevents rotation of the firing arm shaft 100 (to release the arming delay rotor and firing pin) by restraining the firing arm 100. The setback-spin detent arrangement 108 is one of the safety features incorporated into the fuze to provide safe handling and consists of a spin-actuated safety lever 112 restraining the firing arm and a setback pin 109 which is spring loaded at 110 and restrains the safety lever 112. A firing pin 114 spring loaded at 116 is incorporated into this module and is restrained by the firing pin release lever 94 (see FIG. 4). The rotor detent release lever 96 has a rotor release detent pin 118 which restrains one of the two boresafe arming delay rotor spin detents 120 in the boresafe arming module 32. The D-slots 98 and 99 on the firing arm shaft are arranged to actuate the rotor detent release lever 96 a finite period of time prior to actuation of the firing pin release lever 94.

The boresafe arming delay module 32 (shown in FIG. 6)

provides the major safety and arming feature of the fuze. T he boresafe arming delay module uses an unbalanced eccentric rotor to normally hold a stab detonator out-of-line with an explosive output lead. Centrifugal force releases the two independent detent locks on the rotor and drives the rotor towards arming against the inertial restraint of a gear train and runaway escapement. The interlock from the arming and firing trigger module permits one of the detent locks to release only as determined by the position of the timing scroll. An arming delay rotor 122 carries a detonator 124 retained in the opening 125 and which is normally in an out-of-line position with respect to the firing pin 114. The rotor is held in this position by the two spin detents 120 and 126. The detents are held in place by the detent springs 128, with the detent 120 restrained by the rotor detent release lever 96. A properly sequenced firing environment (i.e., setback and spin) will actuate the rotor detent release lever 96 and the spin detents 120 and 126, al lowing the rotor 122 to rotate to the inline (armed) position. Motion of the rotor is controlled by a runaway escapement with its arming rate dependent upon the spin rate to which it is subjected. The physical relation is such that arming distance isv constant in any single weapon except for tolerances. The arming distance depends on the twist and the bore of the weapon only. Several improvements are thus provided by the boresafe arming-delay module. These include:

1. Increased strength to withstand at least 30,000 g. setback and to operate while driven by spin from less than 2,000 rpm. to at least 30,000 r.p.m.;

2. Redesigned center of gravity position to arm reliably when subjected to at least 0.060 inches spin axis eccentricity;

3. Increased angle of freewheeling stroke while disengaged from the gear train to reduce and almost eliminate the time of flight and, hence, the range, during which the fuze is no longer safe but is not yet reliably armed while the detonator is approaching its aligned position.

The explosive train consists of three major components: a detonator 124, a multipurpose lead 132, and the PD elements 134. The detonator 124 is housed in the rotor 122 of the boresafe arming delay module 32. The multipurpose lead 132 has the capability of properly initiating both high explosive and propellant and is housed in the lower body at the base of the fuze. The multipurpose lead is an explosive element that is to be initiated by a relatively small detonator element and in turn is to either initiate detonation of conventional high explosive boosters as used in artillery shell or to'initiate without detonation black powder or propellant materials comprising expulsion charges, flare ignition materials, etc., as used in ar-. tillery shells. When the rotor 122 is in the armed position, the detonator 124 is in-line" with the lead 132. The detonator can be initiated either by the firing pin or'by the PD elements. The PD elements consist of a percussion-sensitive ring primer 134 at the nose-end of the fuze, above the digital setting module and two mild-detonating (MDF) path s 136 (see FIG. 3) leading from the primer mix 134 to the the. detonator 124.

The design of the firing arm shaft portion of the arming and firing trigger module is arranged so that the angular orientation of the scroll follower pin 104, mounted on the firing arm shaft 100, is related to firing pin 114 andto the'delay arming 122 rotor actuation (see FIG. 7). The timing scroll disc 86 controls the scroll follower pin position (i.e., angular orientation) and its rate of change of position. By incorporating the timing scroll disc 86 and the arming and firingtrigger module 30 (i.e., firing pin and delay arming rotor actuation) into the fuze design, the various fuze functional requirements are achieved.

Referring to FIG. 8, the timing scroll disc 86 rotates in a clockwise path with the scroll follower pm 104 following in a spiral groove 88 when it is operating to actuate the fuze when set for time. The scroll follower pin 104 extends from the firing arm lever 102 into the spiral groove 88. The various scroll follower pin positions on the timing disc 86 and their relation to the fuze function is shown in the FIG. 3. Y

A safe-set position is attained when the timing scroll disc 86 is turned to the extreme counterclockwise position (i.e., setting shaft in extreme clockwise position). This places the follower pin 104 at the safe-set position 140 where it is trapped and further movement of the follower pin 104 is not possible. The safe" indicator flag will appear in the fuze window. The safe-set" position prevents the firing arm shaft 100 from rotating and actuating the firing pin 114 and arming the delay rotor release mechanism 30. The PD settable position is next after the -safeset" position (turning the setting shaft counterclockwise) that will enable the fuze to function by PD only. The position is shown at 148 in the H6. 8. It will remain in this position and, if the clock continues to run, it seats against the shoulder. 149 and stops the clock. The follower 104 will travel in the timing scroll disc until it reaches arming delay rotor release cam surface 142. The firing pin 114 is not released. This setting is indicated by the PD" on indicator flag appearing in the fuze window. Upon experiencing the proper fuze environment (i.e., setback and spin), the arming rotor 122 is released and the detonator 124 is oriented to the in-line" position. The detonator will then be fired by point detonation only.

The particular advantages of the PD element include providing a faster means of explosive detonation than is provided by the more usual blast or flash tube elements; providing a safer means of causing rapid explosive detonation than is provided by either an explosive pellet firing into a conventional blast tube or by a continuous explosive column of conventional size. The PD element could be fired readily by deforming the nose of the fuze as by dropping a fuzed shell on its nose. However, the explosive output of the entire PD element would be entirely contained within even the lightest fuze structure and would not be transmitted to the next element which would be out-of-line under such conditions; and, providing a relatively very compact and simple means of transmitting detonation through'and around a mechanism without requiring extensive structural elements.

On setting for maximum time, the scroll disc 86 is rotated so that the follower pin 104 is at the inner end of the spiral at 150. The preferred maximum time is 200 sec. When a firing environment is obtained (such as being fired out of a gun), the clock starts to run and the scroll rotates at a prescribed rate to reach the arming delay rotor release cam surface ML'Rotation continues to the firing pin release position at which the follower 104 drops through opening; 144 and releases the firing pin 114. This hits the detonator 124 in the rotor assembly 122 and initiates an explosive lead 132.

The T 0" release position corresponds to the point at which the scroll follower pin 104 leaves the time scroll disc contour at 144. With scroll follower pin motion unrestricted, the firing arm shaft is free to rotate and actuate the firing pin release mechanism.

lntennediately, the 0.3 to 200 seconds positions are settable scroll follower pin positions on the timing scroll disc 86 that correspond to a delay time prior to firing pin mechanism actuation (i.e., T O"). These scroll plate pin positions will correspond to the appropriate digital counter settings which are observed in the fuze window. As the timing movement operates, the timing scroll disc 86 turns and the scroll follower pin 104 travels toward the T 0" release position 144. Any time setting from 0.3 seconds to 200 seconds can be made. The minimum time setting requirement (i.e., 0.3 seconds) assures that the minimum fuze set time for firing pin actuation delay will be greater than the fastest expected arming time of the rotor, thereby preventing a dud.from'oc.curring by hav: ing the firing pin released before the detonator 1124 is inline."

When the scroll follower pin reaches the arming delay rotor release cam surface 141 on the timing scroll disc in its travel from a time setting to T 0 release, the arming rotor 1220f the boresafe device 32 is released by the arming delay rotor release mechanism 30. This cam surface allows the scroll follower pin to move out radially on the timing scroll disc 86, allowing sufficient rotation of the firing arm shaft to actuate the arming delay rotor release mechanism.

To operate the digital counter assembly 26, the setting key is rotated causing the pin 57 with its pring 59 to automatically pick up the flag 56. When the fuze is set for delivery, the setting key 36 is rotated clockwise turning the digital counter below 0.00 time. Continued rotation below 0.00 time shows first the flag 56 at its PD position. Further rotation will bring the safe position into view.

The time setting feature for the fuze 20 provides a timedelay period before the arming delay rotor is actuated. Fuze setting is accomplished by mating a setting tool into the noseportion of the fuze, engaging the setting key 36 and turning in a counterclockwise direction from .the safe set position (manually or automatically). The time set into the fuze is read from the three digital counter wheels that are seen through the fuze window. Settings are read on the wheel 52 in seconds (numbered), tenths of a second (graduations) and hundreths of a second, estimated as fractions of a graduation. The wheel 50 indicates tens of seconds and the wheel 48 indicates hundreds of seconds. Thus, the range 0 to 200 seconds is obtained. This obviously could be varied to any range desired. As the digital counter is set, the entire timing mechanism module,

which includes the timing scroll disc 88, is turned clockwise. One turn of the timing mechanism module (corresponding to 50 seconds running time), requires five turns of the setting shaft (a :1 ratio). As the timing scroll disc of the timing mechanism module turns clockwise, the scroll follower pin 104 travels inwardly along the spiral path 88 (Le, the scroll follower revolves counterclockwise). Upon experiencing the proper fuze environment (i.e., setback and spin), the timing movement is allowed to function, the setback pin 109 moves clear of the safety lever 102. The follower pin 104 is enabled to move to the surface 141 on the spiral disc 86. This releases the rotor detent release lever 96, and the release pin 118 travels with it. This then releases the rotor detent assembly 120 which in turn releases the arming delayrotor 122, The timing scroll disc 88 continues to rotate until the scroll follower pin is free of the timing scroll disc, and passes through the slot 144. The firing arm shaft 100 rotates and actuates the firing pin release lever 94 to release the firing pin 114. This initiates the explosive train to explode the projectile.

The fuze is capable of functioning by Point Detonation (PD) under two conditions: l when the fuze is fired in the PD set position after the rotor arming time has elapsed, and 2) when fired with a time setting, after the scroll follower pin has traveled beyond the arming delay rotor release cam surface 141 for a period of time equal to the rotor arming time. Both conditions will assure that the rotor of the boresafe arming delay module 32 is armed and can be fired by PD. PD is accomplished by initiation of the arming delay rotor detonator 124 by the explosive output of a mild-detonating fuze (MDF) 136 in lieu of the timing movement-actuated firing pin. The MDF is initiated by a special impact-sensitive primer 134 at the nose of the fuze, above the digital counter, when impact occurs. The setting key acts as the firing pin for the primer.

The fuze 20 incorporates redundant safety features to as sure handling and bore safety. Bore safety is achieved by having the arming delay rotor detented (at 120 and 126) to keep the detonator 124 in the out-of-line (unarmed) position with respect to the explosive lead 132. Upon firing a properly set fuze, setback and spin detents 109 and 112 are released, and after a time, determined by the fuze setting, the arming delay rotor 122 will be released. (Other detents similar to 109 and 112 are in the timing mechanism 80 and are not shown). When released, the rotor 122 will rotate the detonator 124 to the in-line" (i.e., armed) position in a finite period of time. The rotor will start to arm immediately. The arming delay feature eliminates the possibility of premature explosive train initiation by handling or in the gun bore. 0

Handling safety is provided by the safe-set position on the timing scroll disc 86 and by a variety of spin and setback detents in the various fuze modules. By keeping the fuze set to the safe-set position the scroll follower pin 104 is constrained on the timing scroll disc at 140, thus preventing the firing pin and delay arming rotor mechanisms from actuating. (See FIG. 8.)

Referring to the FIGS. 10 and 11, another form of setting key construction is provided. In this form the setting key 36 is provided with the V-shaped prongs (not shown) which fit into the slots 152 of the clutch assembly plate 154. The spring discs 156 apply pressure for the clutch assembly to frictionally seat on the reduced neck portion 158 of the shaft 44. The threaded extension 160 of the shaft 44 receives the lock nut 162. The body portion 164 of the clutch assembly is keyed directly to the reduced neck portion 158 of the indicator pin portion 165. This pin portion provides the function of the similar pin 57. When the setting key 36 has been rotated so as to turn the scroll member 86 in the maximum time position 150, or in the safe-set position 140, the clutch will slip at a present value to prevent breaking through the shaft 44. This is a valuable safeguard in manual fuze setting. However, this safety feature is even more important with the use of automatic setting means, for the rapid acceleration will not be fatal to the structure, since the slip clutch will prevent breaking. It should be noted that thus the setting key 3115 not only serves to apply torque, but also provides PD firing for the fuze 20. The prongs (not shown) of the setting key, by impact force, are driven into the primer 136, and due to its firing pin shape, explodes the primer mix. 1

The substitution of certain equivalent elements for those selected, or the deletion of certain features, or repackaging inside another envelope shape would be within the scope of the conception. Examples of such changes would include the use of a sliding scale setting readout in place of thedigital counter provided; the reduction of the four-turn timing and setting mechanism to one or more turns, or an equivalent increase of turns either with or without a change in a 50 -second setting time per turn; the provision of a winding-setting arrangement such that greater time settings would cause increased winding of the driving mainspring; the elimination of the arming-delay to timing-module interlock so that the resulting fuze would always start to arm immediately upon exit from the gun muzzle; the elimination of the PD option or employment of an independent inertial impact detonating element in addition to, or in place of, the described direct acting PD element; the elimination or duplication of either of the interlocked setback-released or centrifugally released detent elements in either timing module or the arming and firing trigger module; or the elimination of the delaying gear train from the boresafe module; or substitution of an equivalent mechanism; or elimination of the boresafe module entirely.

We claim:

1. A fuze comprising:

a digital counter setting module;

a timing mechanism module;

said timing mechanism module including a time measuring member;

means in said digital counter settingm'odule engaging said timing mechanism module, to set the fuze for a preselected arming position;

an arming and firing trigger module;

said last named module including means engaging said time measuring member;

a boresafe arming delay module engaging said arming and firing module; detonating means;

a housing retaining said fuse modules; and

said housing including a window whereby the setting of th digital counter setting module is visible.

2. A fuze for an artillery type shell able to withstand setback up to 30,000 g.s and spin up to 30,000 revolutions, said fuze consisting of:

a digital counter setting module, said digital counter module including shaft means;

a flag member adjustably retained on said shaft means;

digital counter means mounted on said shaft means;

a setting gear housing retaining said digital counter module;

said shaft extending therein;

a first gear means affixed to the said extended shaft means gear means in said setting gear housing meshing with said first-named gear means;

timing means extending through said setting gear housing and into said shaft means;

an arming and firing trigger module operatively engaging said timing means;

a firing pin in said arming and firing trigger module;

an arming delay module operative with said arming and firing trigger module; and

an explosive train including detonator means retained by said digital counter module and engaging said arming and firing trigger module.

3. The combination of claim 2 wherein said detonator means includes:

a toroidal ring seated on said digital counter module;

an annular groove in said ring to retain a primer mix; and

lead means extending from said ring to said arming delay module, whereby a firing trigger module pin may stab an explosive.

cludes:

4. The combination of clairiifwherein the timing means includes:

a timing scroll disc member;

said timing scroll disc member having a spiral groove and said arming and firing trigger module includes a scroll follower pin;

said scroll follower pin riding in said spiral groove, whereby the detonator means is actuated when. the follower pin has completed its path of travel in thespiral groove.

5. The combination of claim 4 wherein said timing scroll disc member includes a safe-set position and a point delay and arming delay release position.

6. The combination of claim 2 wherein the timing means ina timing scroll disc member containing a spiral groove therein;

said arming and firing trigger module including a pin follower movable in said spiral groove;

firing pin release means retained in said firing trigger module; and

detent means in said firing pin release means to selectively release said firing pin release means.

7. The combination of claim 2 wherein said arming and firing trigger module includes:

a firing arm shaft operative with said timing means;

a firing pin;

detent release means on said firing arm shaft restraining said firing pin; and

firing arm means engaging said timing means whereby the firing pin is released after a predetermined period of time.

8. The structure of claim 7 wherein said firing arm means includes:

shaft includes a setback spin detent comprising:

a safety lever;

a setback pin restraining said safety lever; and

whereby release of said arming delay rotor and firing pin is restrained to insure safe handling of the fuze.

11. The combination of claim 2, wherein:

said arming and firing trigger module includes a firing pin and a rotor detent release lever;

said arming delay module comprises an eccentric rotor;

stab detonator means in said rotor;

said detonator means normally being with said firing pin;

and

means actuating said eccentric rotor to rotate said detonator into line with said firing pin whereby said detonator actuates an explosive charge.

12. The structure of claim 11, wherein said actuating means comprises:

detent locks in said arming delay module retaining said rotor out-of-line with said firing pin;

said rotor detent release lever engaging said detent means to hold the rotor in position; and

escapement means in said arming delay module actuating said eccentric rotor in accordance with the spin rate of the fuze to arm the missile.

13. The combination of claim 112, v wherein said timing means includes:

a timing disc scroll member having a spiral groove, and scroll follower means on said arming and firing trigger module riding in said spiral groove' and the position of the timing disc scroll permitting the detent locks to release so that the rotor may operate to bring the detonator into line with the firing pin.

14. The combination of claim 2, wherein said explosive train means includes:

a ring primer retained on said digital counter setting module;

a detonator; and

a dual purpose lead actionable by said detonator, and mild detonating paths engaging said ring primer and said detonator whereby an explosive path to said dual purpose lead is provided.

15. In a fuze having a timing mechanism counter mechanism and firing mean:

a digital counter setting module providing preselected positions for the fuze, said counter setting module having counter wheels operatively arranged to provide time settings for the fuze;

a point detonator and safe-set flag member;

a setting shaft extending through said digital counter settin module in operative engagement with said counter wheels and said flag member, said setting shaft actuating said firing means; and

key means engaging said setting shaft to set the preselected positions for the fuze. 

